lodash/internal/shimKeys.js

import isArguments from '../lang/isArguments';
import isArray from '../lang/isArray';
import isIndex from './isIndex';
import isLength from './isLength';
import keysIn from '../object/keysIn';
import support from '../support';

/** Used for native method references. */
var objectProto = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/**
 * A fallback implementation of `Object.keys` which creates an array of the
 * own enumerable property names of `object`.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 */
function shimKeys(object) {
  var props = keysIn(object),
      propsLength = props.length,
      length = propsLength && object.length;

  var allowIndexes = length && isLength(length) &&
    (isArray(object) || (support.nonEnumArgs && isArguments(object)));

  var index = -1,
      result = [];

  while (++index < propsLength) {
    var key = props[index];
    if ((allowIndexes && isIndex(key, length)) || hasOwnProperty.call(object, key)) {
      result.push(key);
    }
  }
  return result;
}

export default shimKeys;